Purchase the game legally here:
http://store.steampowered.com/app/12120/It is a steam game so it is as simple as clicking *install* after that follow these instructions:
1. Go to
http://www.sa-mp.com/download.php and download the client.
2. Go to
http://www.freeinfosociety.com/site.php?postnum=867 to download a 1.0 SA EXE.
3. Open up the file from step 2 and get out the EXE and put it in C:/Program Files/Valve/Steam/Steamapps/Common/GrandtheftautoSanAndreas (Make sure you rename the EXE that originally came with steam before putting this one in there. I name the steam one GTA-SA(steam) just so I don't get them mixed up).
4. Run the client you got from SA-MP.com
It will ask you where to install... Install to C:/Program Files/Valve/Steam/Steamapps/Common/GrandtheftautoSanAndreas
5. MAKE SURE THE EXE THAT CAME WITH STEAM IS RENAMED SOMETHING ELSE AND THE ONE YOU DOWNLOADED IS GTA-SA. Also do not run it through steam.
6. Now open up 'samp' in your San Andreas files and it will ask you where you installed it (see # 3) Create a username and when you try and join Argonath RPG